1. Field of the Invention
The invention relates to an apparatus and a method for processing multimedia data. More particularly, the invention relates to an apparatus and a method for synchronizing audio data and visual data.
2. Description of Related Art
Development of science and technologies leads to the increasing demand for quality of multimedia. Accordingly, the digital audio broadcasting (DAB) standard, a digital technology standard for broadcasting audio streams, has been developed. In comparison with the conventional analog broadcasts, e.g., the analog FM radio, the DAB broadcasts are characterized by high fidelity as well as resistance to noise and co-channel interference. Further, a DAB ensemble is able to include multiple channels within one single bandwidth. Recently, new standards (e.g., the digital audio broadcasting plus (DAB+) standard) that resolve issues existing in the old standard have been widely adopted over various countries.
In accordance with the DAB standard or the DAB+ standard, slide shows containing images and texts may be synchronized with audio broadcasts. For instance, during radio broadcasting, information of the current show or song on the radio may be displayed. Alternatively, when a listener in motion receives the radio broadcasts, the listener is able to acquire regional information, such as weather, discount stores nearby, and so on. Even though DAB/DAB+ transmission of visual data relevant to the radio broadcast is allowed during the radio broadcast, an accurate time synchronization mechanism is absent. For instance, when weather information is broadcast on a radio station, and a weather forecast image is simultaneously transmitted to a listener, due to lack of accurate time synchronization mechanism, the listener may not be able to refer to the image transmitted together with the weather forecast broadcast once the reception quality or the data transmission efficiency is unfavorable. Hence, researchers of this technical field are desperate to develop technologies for synchronously and accurately broadcasting audio data and displaying visual data relevant to the broadcast audio data in good time.